//==========================================================================
// Copyright (c) 2000-2008,  Elastos, Inc.  All Rights Reserved.
//==========================================================================
/*
 * JFFS2 -- Journalling Flash File System, Version 2.
 *
 * Copyright (C) 2001-2003 Red Hat, Inc.
 *
 * Created by David Woodhouse <dwmw2@infradead.org>
 *
 * For licensing information, see the file 'LICENCE' in this directory.
 *
 * $Id: build.cpp,v 1.4 2006/05/16 14:13:32 shijun Exp $
 *
 */
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/mtd/mtd.h>
#include "nodelist.h"
#include "jffs2_misc.h"

static void jffs2_build_remove_unlinked_inode(struct jffs2_sb_info *, struct jffs2_inode_cache *, struct jffs2_full_dirent **);

static inline struct jffs2_inode_cache *
            first_inode_chain(int *i, struct jffs2_sb_info *c)
{
    for (; *i < INOCACHE_HASHSIZE; (*i)++)
    {
        if (c->inocache_list[*i])
            return c->inocache_list[*i];
    }
    return NULL;
}

static inline struct jffs2_inode_cache *
            next_inode(int *i, struct jffs2_inode_cache *ic, struct jffs2_sb_info *c)
{
    /* More in this chain? */
    if (ic->next)
        return ic->next;
    (*i)++;
    return first_inode_chain(i, c);
}

#define for_each_inode(i, c, ic)			\
	for (i = 0, ic = first_inode_chain(&i, (c));	\
	     ic;					\
	     ic = next_inode(&i, ic, (c)))


static inline void jffs2_build_inode_pass1(struct jffs2_sb_info *c, struct jffs2_inode_cache *ic)
{
    struct jffs2_full_dirent *fd;

    D1(printk(KERN_DEBUG "jffs2_build_inode building directory inode #%u\n", ic->ino));

    /* For each child, increase nlink */
    for(fd = ic->scan_dents; fd; fd = fd->next)
    {
        struct jffs2_inode_cache *child_ic;
        if (!fd->ino)
            continue;

        /* XXX: Can get high latency here with huge directories */

        child_ic = jffs2_get_ino_cache(c, fd->ino);
        if (!child_ic) {
            printk(KERN_NOTICE "Eep. Child \"%s\" (ino #%u) of dir ino #%u doesn't exist!\n",
                   fd->name, fd->ino, ic->ino);
            jffs2_mark_node_obsolete(c, fd->raw);
            continue;
        }

        if (child_ic->nlink++ && fd->type == DT_DIR) {
            printk(KERN_NOTICE "Child dir \"%s\" (ino #%u) of dir ino #%u appears to be a hard link\n", fd->name, fd->ino, ic->ino);
            if (fd->ino == 1 && ic->ino == 1) {
                printk(KERN_NOTICE "This is mostly harmless, and probably caused by creating a JFFS2 image\n");
                printk(KERN_NOTICE "using a buggy version of mkfs.jffs2. Use at least v1.17.\n");
            }
            /* What do we do about it? */
        }
        D1(printk(KERN_DEBUG "Increased nlink for child \"%s\" (ino #%u)\n", fd->name, fd->ino));
        /* Can't free them. We might need them in pass 2 */
    }
}

/* Scan plan:
 - Scan physical nodes. Build map of inodes/dirents. Allocate inocaches as we go
 - Scan directory tree from top down, setting nlink in inocaches
 - Scan inocaches for inodes with nlink==0
*/
static int jffs2_build_filesystem(struct jffs2_sb_info *c)
{
    int ret;
    int i;
    struct jffs2_inode_cache *ic;
    struct jffs2_full_dirent *fd;
    struct jffs2_full_dirent *dead_fds = NULL;

    /* First, scan the medium and build all the inode caches with
       lists of physical nodes */

    c->flags |= JFFS2_SB_FLAG_SCANNING;
    ret = jffs2_scan_medium(c);
    c->flags &= ~JFFS2_SB_FLAG_SCANNING;
    if (ret)
        goto exit;

    D1(printk(KERN_DEBUG "Scanned flash completely\n"));
    jffs2_dbg_dump_block_lists_nolock(c);

    c->flags |= JFFS2_SB_FLAG_BUILDING;
    /* Now scan the directory tree, increasing nlink according to every dirent found. */
    for_each_inode(i, c, ic)
    {
        D1(printk(KERN_DEBUG "Pass 1: ino #%u\n", ic->ino));

        D1(BUG_ON(ic->ino > c->highest_ino));

        if (ic->scan_dents) {
            jffs2_build_inode_pass1(c, ic);
            cond_resched();
        }
    }

    D1(printk(KERN_DEBUG "Pass 1 complete\n"));

    /* Next, scan for inodes with nlink == 0 and remove them. If
       they were directories, then decrement the nlink of their
       children too, and repeat the scan. As that's going to be
       a fairly uncommon occurrence, it's not so evil to do it this
       way. Recursion bad. */
    D1(printk(KERN_DEBUG "Pass 2 starting\n"));

    for_each_inode(i, c, ic)
    {
        D1(printk(KERN_DEBUG "Pass 2: ino #%u, nlink %d, ic %p, nodes %p\n", ic->ino, ic->nlink, ic, ic->nodes));
        if (ic->nlink)
            continue;

        jffs2_build_remove_unlinked_inode(c, ic, &dead_fds);
        cond_resched();
    }

    D1(printk(KERN_DEBUG "Pass 2a starting\n"));

    while (dead_fds)
    {
        fd = dead_fds;
        dead_fds = fd->next;

        ic = jffs2_get_ino_cache(c, fd->ino);
        D1(printk(KERN_DEBUG "Removing dead_fd ino #%u (\"%s\"), ic at %p\n", fd->ino, fd->name, ic));

        if (ic)
            jffs2_build_remove_unlinked_inode(c, ic, &dead_fds);
        jffs2_free_full_dirent(fd);
    }

    D1(printk(KERN_DEBUG "Pass 2 complete\n"));

    /* Finally, we can scan again and free the dirent structs */
    for_each_inode(i, c, ic)
    {
        D1(printk(KERN_DEBUG "Pass 3: ino #%u, ic %p, nodes %p\n", ic->ino, ic, ic->nodes));

        while(ic->scan_dents) {
            fd = ic->scan_dents;
            ic->scan_dents = fd->next;
            jffs2_free_full_dirent(fd);
        }
        ic->scan_dents = NULL;
        cond_resched();
    }
    c->flags &= ~JFFS2_SB_FLAG_BUILDING;

    D1(printk(KERN_DEBUG "Pass 3 complete\n"));
    jffs2_dbg_dump_block_lists_nolock(c);

    /* Rotate the lists by some number to ensure wear levelling */
    jffs2_rotate_lists(c);

    ret = 0;

exit:
    if (ret)
    {
        for_each_inode(i, c, ic) {
            while(ic->scan_dents) {
                fd = ic->scan_dents;
                ic->scan_dents = fd->next;
                jffs2_free_full_dirent(fd);
            }
        }
    }

    return ret;
}

static void jffs2_build_remove_unlinked_inode(struct jffs2_sb_info *c, struct jffs2_inode_cache *ic, struct jffs2_full_dirent **dead_fds)
{
    struct jffs2_raw_node_ref *raw;
    struct jffs2_full_dirent *fd;

    D1(printk(KERN_DEBUG "JFFS2: Removing ino #%u with nlink == zero.\n", ic->ino));

    raw = ic->nodes;
    while (raw != (void *)ic)
    {
        struct jffs2_raw_node_ref *next = raw->next_in_ino;
        D1(printk(KERN_DEBUG "obsoleting node at 0x%08x\n", ref_offset(raw)));
        jffs2_mark_node_obsolete(c, raw);
        raw = next;
    }

    if (ic->scan_dents)
    {
        int whinged = 0;
        D1(printk(KERN_DEBUG "Inode #%u was a directory which may have children...\n", ic->ino));

        while(ic->scan_dents) {
            struct jffs2_inode_cache *child_ic;

            fd = ic->scan_dents;
            ic->scan_dents = fd->next;

            if (!fd->ino) {
                /* It's a deletion dirent. Ignore it */
                D1(printk(KERN_DEBUG "Child \"%s\" is a deletion dirent, skipping...\n", fd->name));
                jffs2_free_full_dirent(fd);
                continue;
            }
            if (!whinged) {
                whinged = 1;
                printk(KERN_NOTICE "Inode #%u was a directory with children - removing those too...\n", ic->ino);
            }

            D1(printk(KERN_DEBUG "Removing child \"%s\", ino #%u\n",
                      fd->name, fd->ino));

            child_ic = jffs2_get_ino_cache(c, fd->ino);
            if (!child_ic) {
                printk(KERN_NOTICE "Cannot remove child \"%s\", ino #%u, because it doesn't exist\n", fd->name, fd->ino);
                jffs2_free_full_dirent(fd);
                continue;
            }

            /* Reduce nlink of the child. If it's now zero, stick it on the
               dead_fds list to be cleaned up later. Else just free the fd */

            child_ic->nlink--;

            if (!child_ic->nlink) {
                D1(printk(KERN_DEBUG "Inode #%u (\"%s\") has now got zero nlink. Adding to dead_fds list.\n",
                          fd->ino, fd->name));
                fd->next = *dead_fds;
                *dead_fds = fd;
            } else {
                D1(printk(KERN_DEBUG "Inode #%u (\"%s\") has now got nlink %d. Ignoring.\n",
                          fd->ino, fd->name, child_ic->nlink));
                jffs2_free_full_dirent(fd);
            }
        }
    }

    /*
       We don't delete the inocache from the hash list and free it yet. 
       The erase code will do that, when all the nodes are completely gone.
    */
}

static void jffs2_calc_trigger_levels(struct jffs2_sb_info *c)
{
    uint32_t size;

    /* Deletion should almost _always_ be allowed. We're fairly
       buggered once we stop allowing people to delete stuff
       because there's not enough free space... */
    c->resv_blocks_deletion = 2;

    /* Be conservative about how much space we need before we allow writes.
       On top of that which is required for deletia, require an extra 2%
       of the medium to be available, for overhead caused by nodes being
       split across blocks, etc. */

    size = c->flash_size / 50; /* 2% of flash size */
    size += c->nr_blocks * 100; /* And 100 bytes per eraseblock */
    size += c->sector_size - 1; /* ... and round up */

    c->resv_blocks_write = c->resv_blocks_deletion + (size / c->sector_size);

    /* When do we let the GC thread run in the background */

    c->resv_blocks_gctrigger = c->resv_blocks_write + 1;

    /* When do we allow garbage collection to merge nodes to make
       long-term progress at the expense of short-term space exhaustion? */
    c->resv_blocks_gcmerge = c->resv_blocks_deletion + 1;

    /* When do we allow garbage collection to eat from bad blocks rather
       than actually making progress? */
    c->resv_blocks_gcbad = 0;//c->resv_blocks_deletion + 2;

    /* If there's less than this amount of dirty space, don't bother
       trying to GC to make more space. It'll be a fruitless task */
    c->nospc_dirty_size = c->sector_size + (c->flash_size / 100);

    D1(printk(KERN_DEBUG "JFFS2 trigger levels (size %d KiB, block size %d KiB, %d blocks)\n",
              c->flash_size / 1024, c->sector_size / 1024, c->nr_blocks));
    D1(printk(KERN_DEBUG "Blocks required to allow deletion:    %d (%d KiB)\n",
              c->resv_blocks_deletion, c->resv_blocks_deletion*c->sector_size/1024));
    D1(printk(KERN_DEBUG "Blocks required to allow writes:      %d (%d KiB)\n",
              c->resv_blocks_write, c->resv_blocks_write*c->sector_size/1024));
    D1(printk(KERN_DEBUG "Blocks required to quiesce GC thread: %d (%d KiB)\n",
              c->resv_blocks_gctrigger, c->resv_blocks_gctrigger*c->sector_size/1024));
    D1(printk(KERN_DEBUG "Blocks required to allow GC merges:   %d (%d KiB)\n",
              c->resv_blocks_gcmerge, c->resv_blocks_gcmerge*c->sector_size/1024));
    D1(printk(KERN_DEBUG "Blocks required to GC bad blocks:     %d (%d KiB)\n",
              c->resv_blocks_gcbad, c->resv_blocks_gcbad*c->sector_size/1024));
    D1(printk(KERN_DEBUG "Amount of dirty space required to GC: %d bytes\n",
              c->nospc_dirty_size));
}

int jffs2_do_mount_fs(struct jffs2_sb_info *c)
{
    uint32_t i;

    c->free_size = c->flash_size;
    c->nr_blocks = c->flash_size / c->sector_size;
#ifndef __ELAOS

    if (c->mtd->flags & MTD_NO_VIRTBLOCKS)
        c->blocks = vmalloc(sizeof(struct jffs2_eraseblock) * c->nr_blocks);
    else
#endif

        c->blocks = (struct jffs2_eraseblock *)kmalloc(sizeof(struct jffs2_eraseblock) * c->nr_blocks, GFP_KERNEL);
    if (!c->blocks)
        return ENOMEM;
    for (i=0; i<c->nr_blocks; i++)
    {
        INIT_LIST_HEAD(&c->blocks[i].list);
        c->blocks[i].offset = i * c->sector_size;
        c->blocks[i].free_size = c->sector_size;
        c->blocks[i].dirty_size = 0;
        c->blocks[i].wasted_size = 0;
        c->blocks[i].unchecked_size = 0;
        c->blocks[i].used_size = 0;
        c->blocks[i].first_node = NULL;
        c->blocks[i].last_node = NULL;
        c->blocks[i].bad_count = 0;
    }

    INIT_LIST_HEAD(&c->clean_list);
    INIT_LIST_HEAD(&c->very_dirty_list);
    INIT_LIST_HEAD(&c->dirty_list);
    INIT_LIST_HEAD(&c->erasable_list);
    INIT_LIST_HEAD(&c->erasing_list);
    INIT_LIST_HEAD(&c->erase_pending_list);
    INIT_LIST_HEAD(&c->erasable_pending_wbuf_list);
    INIT_LIST_HEAD(&c->erase_complete_list);
    INIT_LIST_HEAD(&c->free_list);
    INIT_LIST_HEAD(&c->bad_list);
    INIT_LIST_HEAD(&c->bad_used_list);
    c->highest_ino = 1;

    if (jffs2_build_filesystem(c))
    {
        D1(printk(KERN_DEBUG "build_fs failed\n"));
        jffs2_free_ino_caches(c);
        jffs2_free_raw_node_refs(c);
#ifndef __ELAOS

        if (c->mtd->flags & MTD_NO_VIRTBLOCKS)
            vfree(c->blocks);
        else
#endif

            kfree(c->blocks);

        return EIO;
    }

    jffs2_calc_trigger_levels(c);

    return 0;
}
